During the last two decades, it has been shown that cells can directly communicate with each other. That is, there is direct transfer of electrical signals and small molecules from one cell cytoplasm to adjacent cell cytoplasms. Various details governing this type of cell communication have been elucidated. Unfortunately, the cells of the mammalian inner ear have not been included in this research effort. In fact, the existence of cell communication in the inner ear was only proved this year. However, the details which govern these cellular interactions in the inner ear are unknown. There are several factors which are known to affect cell communication in other tissues. The aim of this project is to evaluate the effects of such factors, specifically by altering the intracellular and extracellular microenvironments of the organ of Corti. The role of membrane potential, pH, and Ca++ in supporting cell coupling is evaluated both by intercellular electrical coupling studies and flourescent dye spread studies. In addition, the effects of auditory stimulation and overstimulation on coupling is studied. The microenvironment of the inner ear is critical for the normal functioning of the organ of Corti. The results of this study may provide information as to the role of cell-to-cell coupling in the normal function of the organ of Corti, and may also be significant in understanding pathologic effects upon the organ of Corti under varying disturbances in pH and ionic conditions. In addition, this study may provide insight into the effects of noise exposure upon the organ of Corti.